高砷无烟煤低负荷燃烧过程中砷的释放特性及灰中砷形态分布规律

Study of Release Characteristics of Arsenic and Distribution Pattern of Arsenic Species in Ash During Low-load Combustion of High-arsenic Anthracite Coal

选取高砷无烟煤,采用管式炉研究了低负荷燃煤工况下砷的释放及灰中砷形态的变化规律。结果表明:800~900℃区间内,随着温度的升高煤中砷的释放速率出现明显峰值,灰中As^(3+)占比呈上升趋势;灰中弱吸附态砷在800~900℃区间逐步升高,在900℃时As^(3+)占比达到最大值;1000~1200℃区间内,灰中弱吸附态砷氧化分解,砷酸盐占比增加,促使As^(3+)向As^(5+)转变,As^(3+)占比逐渐降低;O_(2)体积分数的升高促进了灰中As^(3+)的氧化过程;此外,随着炉内煤粉停留时间的增加,煤中砷的释放速率与灰中As^(3+)占比呈现同步变化趋势。

Employing high-arsenic anthracite and employing a tubular furnace,the release of arsenic and the variation of arsenic speciation in ash under low-load coal combustion conditions was investigated.Results show that within the temperature range of 800-900℃,the release rate of arsenic from coal exhibits a significant peak with increasing temperature,while the proportion of As^(3+)in ash shows an upward trend.And the proportion of weak adsorbed arsenic in ash gradually increases within 800-900℃,which reaches its peak at 900℃.Within the range of 1000-1200℃,weak adsorbed arsenic in ash undergoes oxidation and decomposition,leading to an increase in the proportion of arsenate,prompting the transition of As^(3+)to As^(5+),and consequently,the proportion of As^(3+)decreases gradually.The increase of the volume fraction for O2 facilitates the oxidation process of As^(3+)in ash.Furthermore,with the extension of coal particle residence time in the furnace,the release rate of arsenic from coal synchronously varies with the proportion of As^(3+)in ash.